The proposed study will define the functional role of a noel protein, FAC1, during brain development and Alzheimer's disease (AD). The FAC1 gene product has been shown to be expressed at high levels during human brain development, low levels in adult control brain, and re-expressed during early stages of AD. Functional analysis of specific domains within FAC1 is required to understand the role of FAC1in these processes. We have identified a zinc finger motif and acidic activation domain in the N-terminus of FAC1, features common to transcription factors. The first Specific Aim will test the hypothesis that FAC1 interacts with other proteins and assay their ability to regulate FAC1 function. Characterization of FAC1 interacting proteins during brain development and various neurodegeneratie discases will further define molecular mechanisms guiding transcriptional and translational events during these processes.